Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/platform/scroll/ScrollTypes.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 163 matching lines @@
 };
 
 enum ScrollInertialPhase {
   kScrollInertialPhaseUnknown,
   kScrollInertialPhaseNonMomentum,
   kScrollInertialPhaseMomentum
 };
 
 enum ScrollbarOrientation { kHorizontalScrollbar, kVerticalScrollbar };
 
+enum ScrollOrientation { kHorizontalScroll, kVerticalScroll };
+
 enum ScrollbarMode { kScrollbarAuto, kScrollbarAlwaysOff, kScrollbarAlwaysOn };
 
 enum ScrollbarControlSize { kRegularScrollbar, kSmallScrollbar };
 
 typedef unsigned ScrollbarControlState;
 
 enum ScrollbarControlStateMask {
   kActiveScrollbarState = 1,
   kEnabledScrollbarState = 1 << 1,
   kPressedScrollbarState = 1 << 2
@@ skipping 80 matching lines @@
       NOTREACHED();
       return ScrollGranularity::kScrollByPrecisePixel;
   }
 }
 
 typedef unsigned ScrollbarControlPartMask;
 
 }  // namespace blink
 
 #endif